X-ray photoelectron spectroscopy study of radiation-damaged Si-SiO2 interfaces

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Abstract
A direct observation of interfacial defects caused by electron beam irradiation in a scanning electron microscope of device‐quality Si‐SiO2 structures has been made by x‐ray photoelectron spectroscopy (XPS). Radiation‐hard oxides (∼700 Å thick) on Si were subjected to 20‐keV electron bombardment and several annealing treatments. The radiation induces defects at the semiconductor‐oxide interface that were identified by XPS as Si with 3 bonds to oxygen and 1 dangling bond. The state anneals slowly (in a few days) at room temperature but is removed within 30 min by N2 or forming gas (90% N2+10% H2) anneals at 400 °C. Although electron beam irradiation of thin (45 Å) oxide structures is known to produce interface states with similar properties, this is the first report of XPS identification of states produced on device‐quality materials under standard processing conditions (i.e., those used for electron‐beam writing).